Compression worries

[vesselgreenhead]

Please someone help! I have a johnson"93" 115 v4 with with very little hours, actually bought new in "97" still in the box from omc dealer. runs great, don't miss, starts easy and runs 5400 rpm's with 19 pitch prop. a friend of mine gave me a compression meter to test my cylinders. standing from the rear of the motor, the two cylinders to left hit at 125 respectfully however, two the the right hit 120 and 100, over the 15 allowed. is this a problem. i'm freaking out over this difference. can't be time to rebuild or not. please advise. also exhaust on high compression side through exaust hole has black residue after running, nothing on on weaker side.

 

[clanton]

Re: Compression worries

Run a can of engine tuner thru it, follow instructions on can and try compression test again.

 

[vesselgreenhead]

Re: Compression worries

thank you for replying. should i get this engine tuner from omc or do you recomend a certain tuner. is it put in the gas or inserted in carb. or sprayed in the cylinder itself????

 

[vesselgreenhead]

Re: Compression worries

clanton, thank you for your advice, went to west marine today and bought some engine tune, followed directions and retested compression. guess what!!! compression went up to 110 on weak cylinder only ten away from the top cylinder. it worked!!!! maybe in time compression may get even better. do you think i should continue to use this product every so often or that cylinder just happened to have trash in it??? once again, THANK YOU !!!!!!!

 

[12Footer]

Re: Compression worries

This right here is why I swear by the practice of decarbing a 2cycle twice a season. Even some veteren wrenches totally disagree with me, but there ya go.<br />OMC has a fuel additive (also a spray can type) carbon cleaner. I think they make the Seafoam Brand, which is amoung the best.<br />I don't usually reccommend the use of fuel additives such as seafoam, opting for the airesol type...But in you case, do both.<br />Try to get the rest of the compression back,and keep an eye on it after every outing.<br />Then, twice a season, run a can of it thru her, or allways run the additive.<br />Glad to hear you caught it in time. Way to go

<br />Because the stuff can get so bad, (carbon) that nothing short of removing the heads and physicly scraping it out, can help. It also gets under the ring lands of the cylinder, and does all kinds of nasty things to sleaves ,rings and pistons.

 

[12Footer]

Re: Compression worries

I meant ring lands of the PISTONS.<br />Sorry.

 

[krosemond]

Re: Compression worries

12Footer, define a season. Is it the same for the guy that puts 25 hours on the engine as the guy that puts 150? What about if you live in FL, or Maine?<br /><br />Just curious (really not trying to be a wiseguy!). Here in NC, my season is mid April to Mid October, with usage being a bell curve over that timeframe. For instance, I was at the beach last week and ran the engine from 4-6 hours each day for seven straight days. I figure a total of 30-35 hours for the week. <br /><br />That week is in the middle of probably about 25 hours on both sides of the season's "bell curve" of usage. I figure about 80-90 hours per season. Help me come up with a decarb schedule that is enough, but not too much.<br /><br />BTW, I just started this practice this year on the ol'79 sea horse. I did it for the first time in the keys in March, after some bad fuel problems, and then once again after about 20 hours. Am I ready again?